"I would like to thank everyone for their love and support. We ask that our privacy is respected during this difficult time."

Michael Oram, chairman of the Channel Swimming and Piloting Federation, said: "Attempts were made by crew to resuscitate him before a French rescue helicopter arrived with medics who tried further resuscitation."

A speedboat of rescuers from Calais also rushed to the scene, but despite several attempts medics were unable to revive him. A post-mortem examination is due to be held to establish the cause of death.

Casey was raising money for two charities: Marymount hospice in Cork and the Society of St Vincent de Paul. Casey, who worked at Fota Wildlife Park, was a member of the Sandycove swimming club in Kinsale, Co Cork, for the last five years.

Ned Denison, the club's secretary, said his friend was an excellent swimmer and a great man. "He was a lovely bloke," said Denison, who has swum the Channel and was Casey's training partner. "He loved the water and he was in an environment where lots of other swimmers were pushing the distance and Paraic started to swim further and further and further."

Casey signed up for the 35km (21-mile) Channel swim two years ago and intensified his training. Previous achievements include a 16km swim between Cork and Cobh and a relay swim with his wife in Lake Zurich.

"In Dover he was fit and healthy and in great shape, with the appropriate amount of confidence and caution," added Denison. "He was an excellent swimmer."

Ireland's Department of Foreign Affairs confirmed staff from its consular office in Paris were assisting the family.